All methods now check type of self.

Differences.md

@@ -25,7 +25,7 @@ Some features don't cater for constrained systems, and at the same time are not
 ## Known Issues
 Known issues are essentially bugs, misfeatures, and omissions considered such, and scheduled to be fixed. So, ideally any entry here should be accompanied by bug ticket reference. But note that these known issues will have different priorities, especially within wider development process. So if you are actually affected by some issue, please add details of your case to the ticket (or open it if does not yet exist) to help planning. Submitting patches is even more productive. (Please note that the list of not implemented modules/classes include only those which are considered very important to implement; per the above, MicroPython does not provide full standard library in general.)
 
-1. Some functions don't perform argument checking well enough, which potentially may lead to crash if wrong argument types are passed.
+1. <strike>Some functions don't perform argument checking well enough, which potentially may lead to crash if wrong argument types are passed.</strike>
 1. Some functions use ``assert()`` for argument checking, which will lead to crash if wrong argument types are passed/erroneous conditions are faced. This should be replaced with Python exception raising.
 1. <strike>It's not possible to override builtin functions in a general way. So far - no "builtins" module is implemented, so any overrides work within a current module only. [#959](//github.com/micropython/micropython/issues/959)<strike>
 1. There's no support for persistent bytecode, and running bytecode (vs running Python source). [#222](//github.com/micropython/micropython/issues/222)
@@ -44,4 +44,4 @@ Known issues are essentially bugs, misfeatures, and omissions considered such, a
 1. 3-argument slicing is only partially implemented.
 1. <strike>Keyword and keyword-only arguments need more work</strike> [#466](https://github.com/micropython/micropython/issues/466), [#524](//github.com/micropython/micropython/issues/524).
 1. Only basic support for ``__new__`` method is available [#606](//github.com/micropython/micropython/issues/606), [#622](//github.com/micropython/micropython/issues/622).
-1. Bitwise operations on long ints are only partially implemented (x & 0xffffffff idiom for casting signed 32-bit value to unsigned works).
+1. Bitwise operations on long ints are only partially implemented (x & 0xffffffff idiom for casting signed 32-bit value to unsigned works).